Flow Control of Jet Flow by Passive Nozzle Configuration Changes

Shakouchi,; Kito,; Sakamoto,; Tsujimoto,; Andò,

doi:10.1260/1756-8250.1.1.73

Cited by 7 publications

(7 citation statements)

References 8 publications

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“…The centerline velocity distributions had no significantly difference in the range of x/De ≳ 3, where the combined region. It seems that the centerline velocity of the combined flow formed by confluence of the multiple elliptic jets will decay in proportion to x -1 at the farther downstream of x/De > 20, as was the case of the single round jet (Shakouchi et al, 2009;Hussein et al, 1994). Figure 5 shows contour plots of the dimensionless x-axial mean velocity, u ̅/Ub, for multiple round jets with nozzle spacing ratio of l/d = 3 (Teramoto et al, 2018b) and multiple elliptic jets with the same azimuthal orientation arrangement and aspect ratios of a/b = 2.25 and 6.25 obtained at the measurement planes (x/de = 1, 3, 5, 8, 14) where the near field of the exit.…”

Section: Experimental Apparatus and Methodsmentioning

confidence: 99%

“…Figure 4 shows distributions of dimensionless centerline velocity, u ̅c /Ub, for multiple elliptic jets with the aspect ratio of a/b = 2.25 and 6.25, and the same and alternate azimuthal orientation arrangement. The results for multiple round jets issuing from 6×6 square matrix arrangement with nozzle spacing ratio, l/d = 3 (Teramoto et al, 2018b), single circular orifice jet at Re = 5×10 3 (Shakouchi et al, 2009) and single round jet at Re = 9.55×10 4 (Hussein et al, 1994) are also shown in Fig. 4.…”

Section: Experimental Apparatus and Methodsmentioning

confidence: 99%

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Influence of nozzle aspect ratio and orientation on flow characteristics of multiple elliptic jets

Teramoto

Kiwata

Yajima

2020

JFST

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Influence of nozzle aspect ratio and orientation on flow characteristics of multiple elliptic jets Abstract An experimental study is conducted to investigate the flow characteristics of multiple elliptic jets issuing from a 6×6 nozzle array at a relatively low-Reynolds number (Re (= Ub•de/ν) = 4.3×10 3). Two aspect ratios of the multiple elliptic nozzles (equivalent diameter, de, of a nozzle was 6 mm), namely a/b = 2.25 and 6.25, where a and b are the radii of the major and minor axes of an elliptic nozzle, respectively, and two nozzle azimuthal orientations, namely the same and alternate azimuthal orientation arrangements, were used. The mean and fluctuating velocities were measured using a constant-temperature hot-wire anemometer. The multiple jets located at the side of the ambient fluid were stretched due to interactions between the self-induced flow of an elliptic vortex ring and the secondary flow caused by the entrainment of the ambient fluid. For a/b = 2.25, axis switching occurred only once in the range of 1 < x/de ≤ 3 for both nozzle azimuthal orientations. For a/b = 6.25 and the same azimuthal orientation arrangement, axis switching occurred only once at 3 < x/de ≤ 5; axis switching did not occur for the alternate azimuthal orientation arrangement. Thus, the flow characteristics of multiple elliptic jets are influenced by the azimuthal orientation of adjoining nozzles.

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Section: Experimental Apparatus and Methodsmentioning

confidence: 99%

Section: Experimental Apparatus and Methodsmentioning

confidence: 99%

Influence of nozzle aspect ratio and orientation on flow characteristics of multiple elliptic jets

Teramoto

Kiwata

Yajima

2020

JFST

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“…The flow contracts suddenly at the nozzle exit and the velocity vector heads inward. The flow characteristics of a circular jet can be controlled by an orifice nozzle with a contraction area ratio (Shakouchi et al, 2008) or notched orifice nozzle (Shakouchi at al., 2009(Shakouchi at al., , 2011(Shakouchi at al., , 2019. Figure 6 shows the velocity distribution, u/u m and u'/u m , of the jet issued from an orifice nozzle measured by hot wire anemometry.…”

Section: Orifice Nozzlementioning

confidence: 99%

“…It is conceivable to control the flow characteristics of the orifice jet with a notched turbulence promoter. (Shakouchi et al, 2009(Shakouchi et al, , 2011. Figure 14 shows the shape of a notched orifice nozzle.…”

Section: Effect Of Notched Orificementioning

confidence: 99%

“…In this paper, the flow control of jets is examined with the flow characteristics, control methods, and some examples of practical applications. In particular, the effects of the nozzle shape (Fiedler, 1998), the tab, rib, and vortex generator (Samimy et al, 1993, Carletti et al, 1996, Zaman et al, 1999, Miyakoshi et al, 2003, Ito et al, 2018, and the orifice or notched nozzle (Shakouchi et al, 2008(Shakouchi et al, , 2009(Shakouchi et al, , 2011(Shakouchi et al, , 2019, on the characteristics of jet flows including supersonic jet, and suppression of the high speed jet noise by the chevron nozzle (Gutmark, 2006, Munday et al, 2013 are examined. Furthermore, some examples of active flow control (Kral, 2000), for example, using an intelligent nozzle , Kasagi, 2006 are also examined.…”

Section: Introductionmentioning

confidence: 99%

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Passive flow control of jets

Shakouchi

2020

Mechanical Engineering Reviews

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One of the major purposes of fluid mechanics and engineering is to reduce the flow resistance caused by flow friction, flow separation, vortex generation, and other factors. To reduce or eliminate flow resistance, in general, flow control is performed either passively or actively. Passive flow control is performed by changing the flow channel or object shape a little and reducing the total flow resistance. On the contrary, active flow control uses a device requiring power, but it can perform various complex flow controls. In this paper, the passive flow control of jets is examined with flow characteristics, control methods, and some applications because jet flows include the essence of fluid dynamics, such as, boundary layer flow, turbulent flow, shear flow, and flow mixing. In particular, the effects of the nozzle shape, the tab, rib and vortex generator, and the orifice or notched orifice on the flow characteristics of sub-and supersonic jets are examined. Furthermore, the control and suppression of high speed jet noise by a chevron nozzle, some examples of active flow control, and other areas are examined. Globular formation of fine solid particles by flow control, lift control of airplane wings, and the flow control of a NOTAR helicopter without tail rotor are also addressed.

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